The present invention relates generally to a system which can be used when an interventional procedure is being performed in a stenosed or occluded region of a blood vessel, including an occluding device adapted to capture embolic material that may be created and released into the bloodstream during the procedure. The system of the present invention is particularly useful when performing balloon angioplasty, stenting procedures, laser angioplasty or atherectomy in critical vessels, such as the carotid, renal, and saphenous vein graft arteries, where the release of embolic debris into the bloodstream could possibly occlude the flow of oxygenated blood to the brain or other vital organs which can cause devastating consequences to the patient.
A variety of non-surgical interventional procedures have been developed over the years for opening stenosed or occluded blood vessels in a patient caused by the build up of plaque or other substances on the walls of the blood vessel. Such procedures usually involve the percutaneous introduction of the interventional device into the lumen of the artery, usually through a catheter. One widely known and medically accepted procedure is balloon angioplasty in which an inflatable balloon is introduced within the stenosed region of the blood vessel to dilate the occluded vessel. The balloon catheter is initially inserted into the patient""s arterial system and is advanced and manipulated into the area of stenosis in the artery. The balloon is inflated to compress the plaque and press the vessel wall radially outward to increase the diameter of the blood vessel.
Another procedure is laser angioplasty which utilizes a laser to ablate the stenosis by super heating and vaporizing the deposited plaque. Atherectomy is yet another method of treating a stenosed blood vessel in which a cutting blade is rotated to shave the deposited plaque from the arterial wall. A vacuum catheter may be used to capture the shaved plaque or thrombus from the blood stream during this procedure.
In another widely practiced procedure, the stenosis can be treated by placing a device known as a stent into the stenosed region to hold open and sometimes expand the segment of the blood vessel or other arterial lumen. Stents are particularly useful in the treatment or repair of blood vessels after a stenosis has been compressed by percutaneous transluminal coronary angioplasty (PTCA), percutaneous transluminal angioplasty (PTA) or removal by atherectomy or other means. Stents are usually delivered in a compressed condition to the target site, and then are deployed at the target location into an expanded condition to support the vessel and help maintain it in an open position.
In the past, stents typically have fallen into two general categories of construction. The first type of stent is expandable upon application of a controlled force, often through the inflation of the balloon portion of a dilatation catheter which, upon inflation of the balloon or other expansion means, expands the compressed stent to a larger diameter to be left in place within the artery at the target site. The second type of stent is a self-expanding stent formed from, for example, shape memory metals or super-elastic nickel-titanum (NiTi) alloys, which will automatically expand from a compressed state when the stent is advanced out of the distal end of the delivery catheter into the body lumen. Such stents manufactured from self-expandable materials allow for phase transformations of the material to occur, contributing to the expansion and contraction of the stent.
The above non-surgical interventional procedures, when successful, avoid the necessity of major surgical operations. However, there is one common problem associated with all of these non-surgical procedures, namely, the potential release of embolic debris into the bloodstream which can occlude distal vasculature and cause significant health problems to the patient. For example, during deployment of a stent, it is possible that the metal struts of the stent can cut into the stenosis and shear off pieces of plaque which become embolic debris that can travel downstream and lodge somewhere in the patient""s vascular system. Pieces of plaque material can sometimes dislodge from the stenosis during a balloon angioplasty procedure and become released into the bloodstream. Additionally, while complete vaporization of plaque is the intended goal during a laser angioplasty procedure, particles are not always fully vaporized and may enter the bloodstream.
When any of the above-described procedures are performed for example in the carotid arteries, the release of emboli into the circulatory system can be extremely dangerous to the patient. Debris that is carried by the bloodstream to distal vessels of the brain may cause these cerebral vessels to occlude, resulting in a stroke, and in some cases, death. Therefore, although carotid percutaneous transluminal angioplasty has been performed in the past, the number of procedures performed has been limited due to the justifiable fear of causing an embolic stroke should embolic debris enter the bloodstream and block vital downstream blood passages.
Medical devices have been developed to attempt to deal with the problem created when debris or fragments enter the circulatory system following treatment utilizing any one of the above-identified procedures. One approach which has been attempted is the cutting of any debris into minute sizes which pose little chance of becoming occluded in major vessels within the patient""s vasculature. However, it is often difficult to control the size of the fragments which are formed, and the potential risk of vessel occlusion still exists, making such procedures in the carotid arteries a high-risk proposition.
Other techniques which have been developed to address the problem of removing embolic debris include the use of catheters with a vacuum source which provides temporary suction to remove embolic debris from the bloodstream. However, as mentioned above, there have been complications with such systems since the vacuum catheter may not always remove all of the embolic material from the bloodstream, and a powerful suction could cause problems to the patient""s vasculature.
Further techniques which have had some limited success include the placement of a filter or trap downstream from the treatment site to capture embolic debris before it reaches the smaller blood vessels downstream. However, there have been problems associated with filtering systems, particularly since they have not always been able to remove all of the embolic material from the bloodstream. After crossing the stenosis and being positioned relative to the interventional procedure site, a device for enabling the removal of captured embolic material needs to be deployed, and after the interventional procedure has been performed, the device needs to be removed with the captured embolic material therein, in an efficient and effective manner.
What has been needed is a reliable system and method for treating stenosis in blood vessels which occludes the blood vessel at a location relative to the interventional procedure site, to enable the efficient capture of embolic material which may be released into the blood in the blood vessel during the therapeutic interventional procedure. The system and method should further be capable of enabling effective recovery of embolic material captured in the occluding device. The system and method should be relatively easy for a physician to use and should provide a nearly failsafe system capable of removing embolic debris released into the bloodstream. Moreover, such a system should be relatively easy to deploy and remove from the patient""s vasculature. The inventions disclosed herein satisfy these and other needs.
The present invention provides a system and method for capturing and retaining embolic debris from a blood vessel which may be created during the performance of a therapeutic interventional procedure, such as a balloon angioplasty or stenting procedure, in order to prevent the embolic debris from lodging and blocking blood vessels downstream from the interventional site. The present invention is particularly useful while performing an interventional procedure in vital arteries, such as the carotid arteries, in which critical downstream blood vessels can become blocked with embolic debris, including the main blood vessels leading to the brain or other vital organs. As a result, the present invention provides the physician with a higher degree of confidence that any and all embolic debris is being collected and removed from the blood vessel when performing high-risk interventional procedures.
The present invention is deployed in the blood vessel at a location relative to the area of treatment in the interventional procedure site, occludes the blood to capture and retain any embolic debris which may be created during the interventional procedure, and recovers the emboli captured thereby.
In one aspect of the present invention, the system includes a guide catheter, and an occluding device adapted to occlude the blood vessel and to capture and retain embolic material. The emboli-capturing system of the present invention occludes blood flow through the area where the interventional procedure is to be performed and through the occluding device located relative to the interventional procedure site, which is designed to capture and retain friable plaque deposits. Additionally, the present invention enables the recovery of embolic material captured in the occluding device.
In an embodiment of the present invention, the system is adapted to capture embolic material which may be released into a blood vessel during a therapeutic interventional procedure at the site of a lesion in the blood vessel, in a collateral blood supply system adapted to enable the flow of blood to bypass the blood vessel upon blocking thereof and to enable the reverse flow of blood through the blood vessel upon unblocking thereof. The system includes a guide wire, including a distal end, adapted to be positioned in a blood vessel relative to an interventional procedure site. It further includes a guide catheter which includes a distal end, adapted to enable the interventional procedure to be performed, and adapted to be inserted over a guide wire and through a patient""s vasculature to a position in the blood vessel relative to the interventional procedure site. It also includes an occluding device, adapted to occlude and block a blood vessel at a location relative to an interventional procedure site, to be expandable so as to prevent the flow of blood past the occlusion, and to enable the capture of embolic material which may be released into the blood in the blood vessel during a therapeutic interventional procedure. The occluding device is further adapted to be contracted to unblock the blood vessel and enable the recovery of captured embolic material. The system also includes a recovery system, for enabling the recovery of emboli captured in the occluding device. The recovery system includes a recovery device for enabling the recovery of the occluding device and embolic material captured in the occluding device. The occluding device includes a membrane comprised of a material without perfusion holes. The recovery device comprises a recovery sheath, adapted to extend through the elongated shaft of the guide catheter, and to be extendable about the occluding device to enable recovery of embolic material captured by the occluding device, by enabling the trapping therein of captured embolic material during the collapsing and removal of the occluding device.
In a further embodiment of the invention, the system is adapted to capture embolic material in a collateral blood supply system which comprises a vascular system which includes a plurality of vessels, including a common vessel which bifurcates into a pair of branch vessels. The guide catheter is adapted to be positionable in the common vessel relative to the interventional procedure site, and the interventional procedure site may be located in any one or more of the plurality of vessels, such as in one of the pair of branch vessels with the occluding device adapted to be positioned in the other of the pair of branch vessels.
Other features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the invention, when taken in conjunction with the accompanying exemplary drawings.